1. Field of the Invention
The present invention relates to feeding devices for sheet stock used in presses, and more particularly to a feeding device forming an overhead stock loop ahead of the conventional incremental feeder.
2. Prior Art
In the prior art, various types of stock feeders that feed sheet stock such as steel, incrementally into punch presses are known. Further, this material is usually passed through a lubricator that applies a film of lubricant on the sheet of material before the material passes into the incremental feeder. The lubricators generally have drive rollers for moving the sheet, while the incremental feeders are usually either reciprocating drive or "start-stop" roll feeders. In other words, a continuous feed into the press is not made, but an increment or desired length of material is fed into the press after each press stroke so that new material is positioned in the die set for the next stroke of the press.
In the usual set up, the material is allowed to hang downwardly from the output of the prefeeder, such as the lubricator, and then it is raised upwardly to the incremental feeder. The material forms generally a catenary curve so that when the incremental feeder feeds the material, the entire hanging loop has to be lifted. This creates a substantial inertia that must be overcome and this of course makes it more difficult to feed the material rapidly and precisely.